Telephone-exchange system



June l0 1924.

S. B WILLIAMS, JR

Tram-:PHONEv EXCHANGE `SYSTEM 7 sheets-sheet 1 v Filed Dec; 24.

, S. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM )une 1o 1924.

`hun@ l0 '1924. '1,497,082

S. B. WILLIAMS, JR 4 TELEPHONE EXCHANGE v SYSTEM l Smm'ke/ 5. W///ams Jn l june 10 ,1924. r 1,497,082 l s. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM v v Filed Deo. 24, 1920 7 sheets-sheet 4 /n VPH /oK- Samuel 5'. WMM/415 JK' FJ?. .n WW' ,My

June l0 1924.

s. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM Filed Deo.

7 Sheets-Sheet 5 RWM Alfy.

.Fume l0 192%. y l 1,497,082

S. B. WILLIAMS. JR

TELEPHONE EXCHANGE SYSTEMv Filed Dec. 24 1920 7 Sheets-Sheet 6 7 Sheets-Sheet -/mmf0/ Samar/19; W/Y//z/ms /ff S B WILLIAMS, JR A TELEPHONE EXCHANGE SYSTEM Filed Dec. 24

Patented .tune 1U, 1924.

1,497,0&2

SAMUEL B. WILLIAMS, JR., OF BROOKLYN', NEW YORK, ASSIGNOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

Application filed December 24, 192e.

T 0 all whom it may concern.'

Be it known that l. SAMUEL B. VILLIAMS, Jr., a citizen of the United States, residing at Brooklyn, in the county of Kings, State of New York, have invented certain new and useful Improvements in Telephone-EX- change Syste-ms, of which the following is a full, clear, concise, and eXact description.

This invention relates to automatic telephone exchangesystems, and more particularly to systems employing switches of the power-driven type in which the switches are controlled by means of a sender located at a central office.

It is the object of this invention to provide an improved method of transferring registrations from one register to another.

A feature of the invention is the use of a plurality of point finder switches which act as registers, these registers being positioned under the control of another registering device.

In systems of the type shown in an application, Serial No. 393,377, filed July lst, 1920 by A. E. Lundell and J. J. YlkVynne, a set of registers areA positioned under the control of an impulse sending device in accordance with the position assumed by a multi-position switch, termed in'such application a translator switch.

lt is more particularly the object 'of this invention to eliminate the: necessity of vusing an impulse generating device to position a set of registers under the control of a translator switch.

An additional feature ofthe invention is the use of point finder switches to replace the rela)v registers of the above-mentioned application.

Other features of the invention result from the arrangement of the circuits 'which control the setting of the registers and will be clearly apparent from the detailed description which follows.

The invention has been shown and applied to a semi-mechanical systeml of the type shown in the above-mentioned application, Serial No. 393,377. The invention is, however, obviously capable of a wide range of usage,'and is therefore not to be limited to the speciiic'embodiment shown.

ln the drawing, the Various figures show so much ot a telephone exchange system as is necessary to' an understanding of the in- TELEPI-IONE-EXCHANGE SYSTEM.

Serial No. 432,908.

vention. Fig. l shows a link circuit at a cordless operators position and includes va district selector switch and controlling circuits therefor. Fig. 2 shows a link circuit to be used in associating an idle sender with the cord circuit which hasv been taken for use, and includes the controlling circuits of a cord finder switch and a sender selector switch. Fig. 3 shows a portion of the control circuit for setting the sender register relays. Fig. 4 shows a set of counting relays for controlling the operation-of the various selector switches of the system, together with a sequence switch to 'control the progress of operations inthe sender.'

Fig. 5 shows a grou-pv of register relays' and a classv sequence switchv and vits circuits. F 6 shows a portion of an operators key set, together with a multi-position switch which takes a registration in accordance with which otlice keys have been depressed. In Fig'. 7 are shown the circuits of various registers togetherlv withl a controlling sequence switch, which not only controls the multi-position switch of Fig. 6, but also controls the progress offimpulsey transmission in transferring the setting of the relays shown in Fig. 7 to the'relays shown in Fig. 5. l l f A general description ofthe system will first be given in order that the detailed description which follows -may be more readily understood. Y f' i The general operation ofthe system is' substantially similar to that described in the above-mentioned application l' by A. E. Lundell and J. J. lV-ynne, No. 393,377. The operator controlling the district switch shown in Fig. l assigns the trunk shown in such figure after receiving instructions from an A voperator (not shown) over an order wire (not shown).l The A operator then plugs into such trunk causing the operation of signals which inform the cord- 'less'operator, as she will Vbe termed herein'- after, that a call is awaitingextension. The

cordless operator then depresses anassignf ment' key, whereupon the link circuit shown in Fig. 2 is put into operation. 'In practice,

there would be a number of these link circuits under the control 'of an allotter, but

for the sake of simplicity only o ne link. circuit has been shown'. The linkclrcuit is provided at each end with a huntingswi'tch.l y

The cord finder at one end hunts for the district circuit at which the assignment key has been depressed, while the sender selector on the other end ot such link circuit hunts for an idle sender.

The cordless operator is provided with a set of ottice keys, and with a set of numerical keys. The numerical keys correspond to those described in Patent No. 1,345,016, issued June 29, 1920, to A. E. Lundell and F. A. Stearn. The numerical keys have not been shown in the present application in order to avoid needless complication.

rIhe operators otlice key set comprises two rows ot' keys, there being one set ot vertical keys and another set ot horizontal keys. Assuming that there are ten horizontal keys and twenty vertical keys it is obvious that by using these keys on a coordinate basis two hundred combinations may be obtained. The arrangement of the keys on thek key board is shown and described in Patent No. 1,369,003, issued February 22, 1921, to IV. Blauvelt.

After the operator has depressed the assignment ,key she will depress the proper office keys and the proper numerical keys. The multiposition switch shown in Fig. 6, which will hereafter be termed a translator switch, is then put into operation to assume a position determined by the particular otiice key depressed in both the horizontal row and in the vertical row. During the hunting movement of the translator switch, the registration set up on the numerical keys is transferred to the sender register relays (not shown) in a manner substantially the same as in the aforementioned Lundell- Stearn application.

After the translator switch has been positioned, the registers shown in Fig. 7 are simultaneously operated in hunting movements to assume positions in accordance with the position assumed by the translator switch. The test terminalsof the registers are variably wired to the terminals engaged by the translator switch brushes so that each setting ot the translator switch will produce a different setting ot the registers. The translator switch may then be restored and the registration is transferred from the registers ot Fig. 7 to the sender register relays ot Fig. 5. The registers oit Fig. 7 are step-by-step switches arranged ttor motion in one direction only and are preterably similar in mechanical structure to the switch shown and described'in an application Serial No. 317,126 tiled August 13. 1919. by O. F. Forsberg and Il. M. De Vignier. After the registration has been set up on the relays of Fig. 5, the operation of the system is substantially similar to that described in the previously mentioned application, Serial No. 393,377 by A. E. Lundell and J. J. Wynne.

The advantage arising from the use ot the hunting registers is readily apparent even from the above general description. In this system the impulse generating device may be eliminated. In systems wherein a common impulse generating device is employed, an accident to the impulse generating device would cause the delay or multilation ot all calls which were being set up at the particular time the mishap to the impulse generating device occurred. This danger is averted by the present invention. It is also obvious that should it be desired to change the routing ot a call, the only connections which must be changed are the connections from the registers to a particular set `of terminals.

The mechanical structure of the translator switch is immaterial to the inventive idea. In the present embodiment ot the invention the translator switch used is substantially similar to a switch described in Patent No. 1,123,696 issued to E. B. Craft and J. ll. Reynolds on January 5, 1915. In the present case it has been assumed that each ot the multiple brush sets comprises a set ot live brushes. All ot these brush sets are normally inoperative, as is usual in a paneltype power driven selector switch, and any one may be selected in the usual manner and rendered operative upon actuation ot a trip rod which serves to release the live brushes comprising the selected brush set into physical engagement with a section ot the contact bank served by them. Each brush set is arranged to travel over a section of the bank comprising forty terminals. A controlling commutator and associated commutator brushes are provided, this commutator being provided with segments suitably disposed to accomplished the control of the switch in accordance with the principles ot the invention.

A detail description ot the operation ot the system will now be given.

It will be assumed that a subscriber at an outlying manual otlice wishes to originate a call. For the purposes of simplifying the description and drawings. it has been assumed that this call is to be extended to a local desk. This means that no office selectors need be employed since the call is local and there will be no utility tor numerical designation. The numerical keys and registers and their controlling circuits have therefore been omitted.

When the calling subscriber removes his receiver trom the switchhook, he will cause a signal to be lighted before an A7 operators position (not shown). The A operator will respond to this signal by plugging into the answering jack of the calling subscribers line and will then converse with him to ascertain the ottice and numerical designation ol the call. The A disclosed. Suitable circuits for this purpose are, however, shown in Patent No. 1,342,823, issued Juney 8, 1920, to A. E. Lundell and E. H. Clark.

As soon as the A operator has plugged into the trunk terminatingin F ig. 1 in conductors 101 and 102, a'circuit is completed from grounded battery, sequence switch contact 103, right-hand winding of relay 104, conductor 101, through the cord circuit of the A operator and a supervisory relayincluded therein, returning by way of conductor 102, left-hand winding of relay 104, sequence switch contact 105 to ground. Relay 104 is energized in this circuit and cornpletes a circuit from grounded battery, lefthand winding of relay 106, sequence switch contact 107, armature and contact of relay 104 to ground. Relay 106 is energized in this circuit and completes a circuit from grounded battery. through lamp 108, lefthand contacts of sequence'switch spring 109, inner right-hand armature and front contact of relay 106, right-hand Contact of sequence switch spring-110, outer right-hand armature and .front contact of relay l106, lower contacts of sequence switchspringlll to ground. The lamp 108 is lighted to in*- form the cordless operator that the A operator has plugged into the trunk jack. She thereupon depresses a non-locking assignment key 112, thereby completing acircuit from grounded battery, power magnet of sequence switch100, lower contactof sequence switch spring 113, contacts of key 112, to

'f ground, for moving this sequence switch out of posltion 1 and lnto position 2. As soon asy sequence switch 100 leaves position 1, the circuit of relay 106 is broken and this relay deenergizes,

cuit is completed from grounded battery, winding of' relay 201 (Fig. 2), left-hand contacts of sequence switch spring 202, conductor 203, upper left-hand and lower right-hand contacts spring 114, inner right-hand armature and bacl contact of relayy 106', 'upper contactsof sequence switch spring 109v to ground. Relay 201 is energized in this circuit' and completes a circuit fromfgrounded battery, lefthand .vinding of relayv 204. upper contacts of sequence switch spring 205, outer right-hand armature 'and front contact of relay201 to` ground.- lRelay 204 is energized in this cir- Vcuit and 'completes acircuit fromfgrounded In position 2 of sequence switch 100, aciri-` of sequence switch "the operation of' the cordVl linder. `be recalled that relay 204V was energized battery, powerfmagnet ot sequence switch 200, upper right-hand contact of sequence switch spring 206, inner right-hand armature and frontv contact ot' relay 204, .to ground, for moving this sequence switch out of position l and into position 2.

ln position 2 of sequence switch 200, a circuit is completed from grounded battery, winding of 11p-drive magnet 207, lett-hand contacts of sequenceswitch spring 205, outer right-hand armature and front ucontact ,of

relay 201 to ground. Under the control'ofI magnet 207, the cord finder brush shaft is elevated in search of theterniinal sety corre-v y sponding to the district circuit at which the associated assignment key has been depressed. It is to be noted that as soon as sequence switch 200 leaves position 1i, relay 201 is maintained energized over a circuit extending through the lower contactsofsequence switch spring 202, theleft-hand ar-l mature and back contact of relay 208, the

upper right-hand and lower left-hand'contacts ot sequence switch spring -209 to ground.

rlilhe test terminals associated with district switches, whose controlling sequence switches in any other position than position -2, are characterized by the absence of ground.`

Therefore, test relay 208 does not become enr` i ergized until the cord finder test brush 210 engages test terminal 211,' whereupon a cir-v i cuit is completed from grounded battery,

winding of relay 208, upper contact of'sequence switch spring 212, test vbrush 210,

test terminal 211, conductor 213, yupper con-` tacts of sequence switch spring 115, outerv right-hand armature and back contact of relay 106, lower contacts of sequence switch spring` 111 to ground. Relay 208 is energized and at its left-hand armature opens the circuit of relay 201. Relay 201 remains energized for an instant longer dueto a lockf ing circuit extending from its inner rightsy hand armature and front contact, commutator 214, commutator brush 215 tol ground.

`When an instant later, commutator brush i 215 engages an insulating segment of com-It mutator 214, at which time the cord finder-y brush 'set willbe accurately centered on the seiected terminal-set, relay 201 is denergized and opens at its outer right-liand armature? the driving circuit Ioimagnet 207, which' de-l energizes and allows the cord finder to come to rest. The deenergization of. relay: 201 completes a circuit from grounded battery,

power magnet of sequence switch 200, lower` y left-hand contact ot sequence switch spring 206. outcriight-hand armature and back contact ot relay 201 to ground, for movin this sequence switch out of position 2 an into position 3. l Y Y y *A A* The operation of 'the sender selector 'shown at the right of Fig. 2v is simultaneous with It; will upon the in-itial energization of relay 201 to cause' the advance ot' sequence switch 200 into position 2. Vhen sequence switch 200 leaves position 171, the energizing circuit of relay 204 is interrupted at the right-hand contact of sequence switch spring 205, but if at this time the irst sender is busy, which will be indicated by the fact that its controlling sequence switch 300 is in some position other than 1, a locking circuit is completed through the lett-hand winding of relay 204, left-hand armature and front contact of relay 204, left-hand contacts of sequence switch spring 216, sender selector brush 217, which is engaging test terminal 218 of the set of terminals associated with the first sender, conductor 219, right-hand winding of relay 301, upper left-hand and lower right-hand contacts of sequence switch spring 302 to ground. lith sequence switch 200 in position .2, a circuit is completed from grounded battery, winding of up-drive magnet'220r of the sender selector', contacts of sequence switch spring 221, inner right-hand armature and front contact' of relay 204 to ground. Magnet 220 is energized in this circuit and causes the sender selector brush shaft to be moved upward in search of an idle sender. As soon as test brush 217 engages a test terminal 218 on which there is no ground potential, the locking circuit of relay 204 is broken. -Relay 204 is maintained energized a moment longer, however, due to the existence of a circuit extending from grounded battery, right-hand winding of relay 204, lower left-hand and upper right-hand contacts of sequence switch spring 222, conducting segment of commutator 223, commutator brush 224 to ground. When, a moment later, brush 224 engages an insulating segment of commutator 223, at which time the sender selector brush set will be accurately centered on the terminal set of an idle sender, the circuit through the right-hand winding of relay 204 is broken and this relay deenergizes, causing in turn the deenergization of up-drive magnet 220, thus bringing the sender selector to rest. It is to be observed that if the sender selector is the iirst to complete its operation the sequence switch 200 will remain in position 2 until the cord nder has completed itsy operation, whereupon it will be moved into position 3. The deenergization of relay 204 then completes a circuit :trom grounded battery, power magnet of sequence switch 200, lower right-hand contact of sequence switch spring 20,6, inner right-hand armature and back'contact of relay 204 to ground, for moving this sequence switch out of position 3 and into position 4.

I- the cord iinder is the -first to complete its operation, the sequence switch 200 will be advanced out of position 2 and into position 3 as previously described. In position 3,

the operation of the sender selector will continue as above described, since the circuits therein traced in each case' function to the same purpose whether the sequence switch is in position 2 or position 3 as may be readily ascertained by inspection of the drawing.

As soon as the sender circuit shown in Figs. 3, 4 and 5 has been seized and the sequence switch 200 has reached position 4, a circuit is completed from grounded battery, left-hand winding of relay 301 (Fig. 3), upper right-hand and lower left-hand contacts o't' sequence switch spring 303, conductor 304, terminal 225, brush 226, righthand contacts of sequence switch spring 227, to ground. Relay 301 is energized in. this circuit and locks up through its lett-hand armature and front Contact to conductor 219 which is grounded by way of the upper lefthand and lower right-hand contacts of sequence switch spring 216. Ground potential is also supplied to test terminal 218 to render this sender non-selectable to other hunting sender selectors. Relay 301 upon energization also completes a circuit from grounded battery, power magnet of sequence switch 300, lower left-hand contact of sequence switch spring 305, right-hand armature and front contact of relay 301 to ground for moving this sequence switch out of position 1 and into position 6.

With sequence switch 200 in position 4 and sequence switch 100 in position 2, a circuit is completed from grounded battery, right-hand winding of relay 204, left-hand contacts of sequence switch spring 222, inner right-hand armature and front contact of relay 228, which was energized when test relay 208 operated incident to the finding of the desired cord, cord finder brush 229, terminal 230, conductor 231, lower contact of sequence switch 116 to ground. Relay 204 is energized in this circuit and completes a circuit Jfrom grounded battery, power magnet of sequence switch 200, upper right-hand contact of sequence switch spring 206, inner right-hand armature and front contact of relay 204, to ground for moving this sequence switch out of position 4 and into position 5.

As soon as sequence switch 200 reaches position 5, a circuit is completed from grounded battery, power magnet of sequence switch 100, conductor 117, lower contacts of sequence switch spring 118, conductors 119 and 120, terminal 232, brush 233, outer left-hand armature and front Contact of relay 228, upper contact of sequence switch spring 234, to ground, for moving sequence switch 100 out of position 2 and into position 3.`

As soon as sequence switch 100 leaves position 2, the energizing circuit of relay 204 is broken and this relay deenergizes and completes a circuit from grounded battery, power magnet orn sequence switch 200, lower right-hand contact of sequence switch syn-ing 206, inner right-hand armature and back contact of relay 204 to ground 'for moving this sequence switch out ot' position 5 and into position 6.

As soon as sequence switch 10() reaches position 3, a circuit is completed from grounded battery, lett-hand winding of relay 106, lower right-hand Contact ot sequence switch spring 121, lower contact of sequence switch spring 123, to ground. Relay 106 is energized and completes a circuit from grounded battery, power magnet oit sequence switch 100, conductor 11T, letthand contacts of sequence switch spring 124, inner right-hand armature and front contact ot relay 106, upper contacts of sequence switch spring 109 to ground for moving this sequence switch out ot position 3 and into position 5. As soon as sequence switch 100 leaves position 8, the energizing circuit of relay 106 is broken and this relay deenergizes. The district sequence switch remains in position 5 until the fundamental circuit 't'or controlling the selective operation oi the switch is completed.

The operation of setting up the wanted oiiice designation on the various registers will now b@ described. As previously mentioned, the operator is provided with a set ot keys to control otiice selection comprising a row of horizontal keys indicated genen ally at H in Fig. 6 and numbered trom 1 to 10 and a row of twenty vertical keys shown generally at V, Fig. 6, and numbered from 1 to 20. She is also provided with a. keyset provided with ten keys tor veach digit a wanted number, these ten keys representing respectively the ordinals from 0 to 9. The numerical keys and the method in which they function to control registers will not be described. i

The incoming call is to be diverted to the attention of an operator at a local desk. Assuming' that the oiiice code corresponding,r

to a call which is to be routed to a local desk is AX, the cordless operator will ini- 'mediately after depressing assignment key 112, as previously described, depress key No. 7 in the H row and key No. 15 in the V row.v

As soon as key A is depressed, a circuit -is completed from grounded battery, windthis sequence switch out'of lposition 1 and into position 2. As soon as sequence switch 700 reaches position l, relay 701 completes a locking circuit :tor itself through its right-- hand armature and front contactand the left-hand armature and back contact 'ot' relay 708 to ground by way ot the upper lefthand contact of sequence switch spring 709.

In position 2 of sequence switch 700, brush selection is accomplished by the translator switch shown in Fig. 6.I rlhe circuit ot updrive magnet 601. extends from grounded battery, winding of magnet 601, conductor 602, upper lett-hand and lower right-hand contacts of sequence switch spring 710,` lefthand armature and front contact ot relay 701. to ground. It is to be observed that with sequence switch 700 in position 2, relay 603, Fig. 6, is energized over a.1 circuit extending from grounded battery, winding of relay- 603, conductor 604, right-hand contact ot sequence switch spring 711 to ground.

During the upward movement of the translator brush shatt, commutator test brush 605 successively engagesthe commutator segments in the right-hand group kot the main colnmutator plate 606. The tirst tive contacts to be engaged by brush 605 are utilized to determine which set ofbrushes shall. be selected. Each brush set serves a group of forty terminal sets. 'These forty terminal sets are arranged'in a continuous group. A special controlling circuit ar` rangement is used, v the operation of lwhich will be subsequently described, so that in case the desiredV terminal set is in the lower twenty, the selected brush set will begin hunting, starting from thelowermost'terminal in the lower twenty. In lcase, however, the desired terminal set is in the upper twenty, the selected brush set will be moved' over the contacts of the lower 'twenty without limiting in such group and will 'come to rest with its brushes in engagement with the lowermost terminal set in the upper twenty. Thereafter it will be caused to hunt yfor the proper terminal set. From thisit is obvious that the selection of the desiredl onefol'- two hundred terminal sets is accomplished,first, by selecting one of tive brushes'to selecta group of forty terminals.v Selection is uthen made to select an upper or lower group ot twenty terminals, atter which the desired terminal is selected. The selection oit a brush set and the selection Yot a twenty v group yis made under the control of a key in the horizontal column. The selection ot thev particular Contact in the twenty group' is always under the control ot' a key in the vertical column. 'i

The translator brush shaft is moyedup` wardly as described until comniutator brush 605 engages commutator segment'607, at which time a circuit is completed from grounded battery, winding i of relayv 708,

lli-0 Vil right-hand contacts of sequence switch spring 712, conductor 713, brush 605, segment 607, armature 608 and its front contact, conductors 609 and. 610, closed lefthand contacts of key A, conductor 611, lower right-hand contact of sequence switcn spring 709 to ground. Relay 708 is energized in this circuit and locks up to ground through its right-hand armature and the upper right-hand contact ot sequence switch spring 709. Relay 708 at its lett-hand armature opens the locking circuit of relay 7 01. Relay 701 is maintained energized a moment longer, however, due to the existence oi" a circuit extending by way of conductor 714, a lconducting segment of commutator 612, commutator brush 613 to ground. lVhen, a moment later, commutator brush 613 engages an insulating segment of commutator 613, atwhich time the selected brush set will be accurately positioned for brush tripping, relay 701 is deenergized and at its lett-hand armature opens the circuit of up-drive magnet 601, causing the translator brush shaft to be brought to rest. The deenergization ot relay 7 01 also completes a circuit iti-om grounded battery, power magnet of sequence switch 7 00, conductors 705 and 706, lower left-hand contact of relay 701 to ground, Yfor moving this sequence switch out ot position 2 and into position 3.

In position 3 of sequence switch 700, a circuit is completed from grounded battery, winding ot trip magnet 614, conductor 615, right-hand contact of sequence switch spring 711 to ground. Trip magnet 614 is energized and operates the trip rod controlled by it so that upon the subsequent upward movement of the translator switch, the second set ot brushes will be released into operative relation with the group ot terminals served by it.

The keys numbered from 1-5 inclusive in the horizontal row are arranged to cause a selected brush set to hunt for a particular one of twenty terminals in the lower twenty of a selected group of forty terminals. This is accomplished due to the tact that ground is supplied to conductor 720 by way of the right-hand contacts of such keys when actuated. Any one of keys 6 to 10 in the horizontal row when actuated determine that hunting for the desired terminal set shall take place after the lower twenty `group has been traversed. This is accomplished by Asupplying ground to conductor 704 by way of the right-hand contacts ot such keys. The manner in which the discrimination between twenty groups is accomplished will now be described.

Since key A. has been depressed, which is one of, the keys numbered 6 to 10 in the horizontal group, the desired terminal set is located in the upper twenty. Therefore, with sequence switch 700 in position 3, a circuit is Mer/,cee

completed Jfrom grounded battery, winding of relay 701, upper' right-hand contact of Sequence switch spring 702, conductors 703 and 704, closed right-hand contact of key A, conductor 600 to ground. Relay 7 01 is energized in this circuit and locks up through its right-hand armature and front contact and the left-hand armature and back contactJ ot relay S, which was deenergized when sequence switch 700 lett position 2, to ground by way of sequence switch spring 709. Relay 701 at its lett-hand armature completes a circuit Jfrom grounded battery, power magnet ot sequence switch 700, upper righthand Contact of sequence switch spring 707, lett-hand armature and front contact of relay 7 01 to ground for moving this sequence switch out or" position 3 and into position 4.

Tn position 4 o1c sequence switch 700, a circuit is completed trom grounded battery winding ot up-drive magnet 601, conductor 602, upper left-hand and lower righthand contacts of sequence switch spring 710, lett-hand armature and front contact of relay 701 to ground. No test of the terminals in the lower twenty is made as comniutator brush 605 passes over the commutator segments corresponding to such terminal sets. However, as soon as test brush 605 engages the commutator segment corresponding to the lowermost terminal set in the upper group of twenty, which is segment 618, a circuit is completed from grounded battery, winding of relay 708, right-hand contacts ot sequence switch spring 712, conductor 713, brush 605, terminal 618, conductor 699, lower lett-hand contact of sequence switch spring 715, conductor 704, closed right-hand contacts of the A key, conduct-or 600 to ground. v:Relay 708 is energized in this circuit and at its left-hand armature opens the locking circuit of relay 701. Relay 701 remains energized as previously described until the brush set is accurately centered, whereupon it deenergizes and completes a circuit from grounded battery, power magnet of sequence switch 700, conductors 7 05 and 7 06, lower left-hand contact of sequence switch spring 707, lefthand armature and back contact of relay 701, to ground, 'for moving this sequence switch out of position 4 and into position 5. Relay 7 08 is deenergized as soon as sequence switch 700 leaves position 4.

As soon as sequence switch 700 reaches position 5. a circuit is completed from grounded battery, winding oit relay 7 01, conductor 71.6, contacts ot sequence switch spring 853, conductor 71.8, closed right-hand Contact ot key X, conductor 619 to ground. Relay 7 01 is energized and completes a circuit for moving sequence switch 700 out of position 5 and into position 6, identical with the circuit traced for moving it from position 3 to position 4. Relay 7 01 upon enerli'i gizationf locks u-'p i tliro'ughrf.the,V left-hand armature' and back Contact otvrelay 708 as Apreviouslydescribed." .Y 1. f

. In' Aposition 6'vv ot" `sequenre #switch f 700 the translator switch iis moved upwardly in fitslinal huntingmovement, theoircuit of up-drive magnet 601 extending to4 ground at the left-hand 'arma-ture and front. contact of relay 701 over a path previously-described. When test brush-605 engages coinmutatorsegmen't 620, Whichl is the'segi'nentinl l'the uppertiventy, associatedv ivithfley TQ-va cir*- cuit is y `completed from grounded battery, Winding otrelay'708, contacts of' sequence switch spring 712, conductor 716, brushttl, segment 620, conductor-11621,y closed left-hand contact ,of key 3X, conductorv 622, upper right-hand contact'- ot lsequence lswitch"spring 851i to ground;*Relay"708frisrenergiz'ed in this circuitand :opens at its left-hand armayture'fthe'locking circuit of relay 701;? ll/lien,

a moment-later, commutator brush-6l3 enlages f an'insulating segment lof commutator A6112-, relay 701 deenergizesand openscrthefcircuit of up-drive magnet `601,"allovin'gwthe translator 'brush-shaft to come-'ite restwith the Second set of 'brushes inI engagement ivith the thirty-fifth terminal' set-in the groupfservecl itfRelay 7 01upon -deenergization, 'alsofcompletes a@ circuit from grounded battery, powe'r'magnet of sequence switchv '700, conductors 705 and 706, lower -contact Io tfrs'equen'ce'switch spring 7 07,lefthand arma-ture and baclr'c'ontact'- of relay y701' to 'ground vlfori lnovingtliis :sequence switch.outoit-position-6and into Iposition 7.

position `3. "'Nociircuit Vis -found forfrelfay 7 014 in position lofi sequence switch 7001mder the" assumptions sthat haf\fe-nowb een made." Sequence sivitclii700. is however, 'iin'- mediately moved jout oftposition f3 4by' means 'ofj a circuit extending freni groundedibate tery, power magnet of sequence switch 7500, conductors 705 i and upper' "left-hand contact of' sequence switch spring 7 07,-A -coir ductoi '720,V "closed` righth'and contacts of 'key E tof-ground." As Asoon as "sequence switch700 yreaches position 4, itis immediately moved out of position 4C and into posi,- tion 5 by means ofa circuitextending from grounded battery, power ,magnet-'ot :sequence switch 700, 'conductors"705`and 706, llower vover 'grounded battery. left-hand- Windii ci said relays to ground by Way ot" thele'ft- .hand contacts of sequence switch springs left-hand" Contact; :et sequence Vswitch spring 707, lett-hand armature and b-aclr contact :ot relay 7011 to ground. Sequence switch/700 is. then moved out of position 5 and into 'postion 6 by-means -of circuitsl previously:` described. la positionv 6," .up-'drive magnet 601 is again' energizedandtheA 'translator brush. shaft is moved fupwardlyx-When commutator brush 605y engages commutator segment 623,V ya circuit .1s,conipleted Tlf-rom grounded battery, Winding of relay'708g, con'- tacts of sequence switch spring 712,' conductor 713,-brush 605, terminal 62S, conductors 624 and 621s, closed left-hand contacts ot lrey X andthence to ground as previously described. In .th-is casegthe translator brush is brought to rest'with `its selected brush set in engagement with thefiifteenth contact set in thegroupy of `terminals served byit. i f

Ass-soon as thetranslator. sWitclr'fISPO- sitioned, the first transfer 'of `the'V oliic'e registration has been accomplished,"since the po'- sition assumed by vsaid translator switch determines what 'districtf and office selections are to be made.- The method of transferring this lregistration Yfrom'the translator switch to the step-'by-step registers et Fig..71-"Will now be described..g w 'Vf `llVhen sequence switchl700 is 'movedbutot position 6 as a result of the finding o'lthe desired setr of Iterminals in the* translator contact baclr`,the registersofwF'igf-Tiare broughtinto operation;l f f When sequence sWitchI-700-reache's pos 'n (Sycircuits are completed4 'for rfflays 810;:811, 812, S813' andSlll, rthesey circuitsextending 664i, 665,666, S67 and Stifrespectively:

1W hen sequence switch 700 reaches position v(Sl-,a locking circuitis completedllior' relay *810:` extending from grounded batterygf-inner right 1h and f' armature :and front contacty of relay 8'L0,righ"t hand winding"ell 'relayi 810,

theloiver'contacts of sequence switchI spring 859 to ground through a resistance.- Similar locking circuits'are also completed lforrelays 811 to S14' inclusive. f With Vsequence switch 700 iin 'positi n I7 7 Ain which positron' it Wil-lv lremain vuntil` all 4the registers have been positioned, vrelays'l() 'to 61d` arey maintained energized byl means 'of the above described holding 'circuitsr and circuits ar'e completed 4'ttor the stepping' magnets ot' the 'various registers.' lThe circuit ot' stepping magnet 815 otlftl'i'e vvclass` register switch extends trom, grounded"battery, vririding",` armature and back Contact of mag-- net 81,5. outer right-h'and, armatiireanrl ,front contact ot relay 810,l v4right-hand contact of sequence switch Spring 864 tog'round. Magnet 815 i's energized in this'circuit and interrupts its 'ofWn'circuit-'to cause the afd- Vance of the brush set controlled by it in a hunting movement insearch of a terminal as determined by the position of the translator switch. rIhe brushes operated by each stepping magnet have been placed in a lateral row to the right of the various stepping magnets respectively. Relay 815 continues tointerrupt Iits circuit until test brush 820 engages its fourth off` normal contact, at whichtime relay 810 is deenergized due to the presence of a direct shunt about its Winding. This shunt circuit extends from grounded battery, vtest brush 820 and-its fourth contact, conductor 677, terminal 669, brush 670, conductor 671,y lower left hand contact of sequence switch spring 859 to ground. The deenergization ofi relay 810 opens the driving circuit of stepping maginet 815 and brings the register controlled by it to rest. It is to be noted that while testbrush 820 is passing over test terminals other thanl that to which lead 677 is connected, relay 810 cannot be shunted down, since even though a terminal whichl is connected to a multiple terminal corresponding to 669 on `which some other translator switch is positioned and even though the sequence switch corresponding to sequence switch 700, which is associated with such other translator switch should bein position 7 relay 810 ywould sti'llfnot be shunted down, since in this; case current flow would be" through a resistance to ground-at. such other translator switch. This would have, of course, some shunting actionon relay 810, b-ut not 'suiiicientv to cause its deenergization, vthis relay being so designed thatv a small current flow will be sufficient to maintain 'inl an energized condition. However, when "testbrush 820 engages a terminal which is `wired to a translator switch' terminal on which the translator switch of Fig.- 6 is positioned, it is `obvious thatthe winding of relay 810 is completely short-circui-ted, and that no current at all can iow through its winding.

`The hunting operation of the other registers will not be described, since their operation is in everyjway identical with thatdescribed for the class register 'controlled by stepping magnet 815. The 'completion of the hunting movements of all registers vleaves the class register controlled by magnet 815, in its fourth off normal position; thedistrict brush register controlled by magnet 816, in its fourth oli normal position; the district group register, vcontrolled by magnet817 in its sixth ofi normal position; the ofice brush register, controlled by magnet 818, in its first off normal position and the otiice group register controlled by magnet 819, lin its tenth off normal position.

As soon as all the registers are positioned, at which time relays 810 to 814 inclusive will all have been deenergized, a circuit is completedlfromV groundedbattery, power v magnet-'of sequence switch 700, lowercontact of sequence-'switch spring'772 and thence in series through the IetJhand-armatures and back contacts of relays" 810 to 814 inclusive to ground. T'hecompletion of this-circuit advancessequence switch 7 00 out ofrposition 7 and into position'8. 1

As soon as sequence switch'700freaches position ,8, a `circuit iis completed from grounded battery, winding. o-down-drive lmagnet 67 9, conductor 680, lower contact of sequence switch spring-858 armature and back contact ofA relay 869 to` ground. The translator switch is returned y'to its normal position underthe control of magnet- 679 and when the translator brush 'shaft reaches its normal:V positionas evidenced' by the engagement 'of` commutator-brush 613 -with -normalcommut'atr segment 681, a circuit is completed` from groundedbattery, winding of relay 869, contact of sequence switch spring 87.0, conductor 773, commutator seg ment 681, brush 613 to ground. VRelay 869 is energizedand opens-'the circuit lfor downdrive magnet 67 9.

The operationl ofy transferring the registration rom the register switches of Fig.v7 to the relays of'Fig. 5 will nowbe described.

-When sequence. switch 7 0() reaches position 7 a circuit is completedfromground ed battery, right-handfwinding of relay 502 (Fig. 5), conductor- 503,\-l`ower contacts of sequence switch spring-308, closed due to the fact that sequence switch 300 is inposition 6, condu'ctors'BOQ, 310 and 811,v terminal 240, brush 241, conductors 2421 and 243, upper left`andlower'right-hand` cont-acts of sequence switch spring 244, conductor k245, contact of sequence switchv spring 830, regis- -ter armug825 and its fourth contact to ground.. kRelay 502 is a marginal relay-but due to the fact th'atldirect lg-round is supplied -to its rightfhand winding, it becomes energized and locks up-through its lleft- -hand armature toconduct0r/504,which is grounded' at the upper righthand contact of sequence switch spring 3,12.

When ysequence switch 700 -reachesposition 8, a circuitlis completed when grounded battery, right-hand winding of relay 500 (Fig. 5),'conductor 501, upper contacts oiu sequence switch spring 306, conductor 307, terminal 285,` brush 1236, conductor` 237, -lower contact of sequence switch spring 238, conductory 239, contact of sequence'switch spring 840, lregister brush ,1835, and its fourth contact, conductors j 871 and 872, right-'hand andleft-hand windingsl of relay 777 inl series, uppervarmature andy back contact of relay778to ground. Relay 777 is energized "in thiscircuit, but marginal relay 500 isnot energizeddu to the Ifact that 'the `high resistance winding of relay 777 was included in-this circuit. l Relay 777 jupon ener gi-zation locks up -throughits inner left-hand armature and front contact, and in so doing removes the shunt from about the winding of relay 778, allowing this relay to be energized due to the completion ofy a circuit extending fromv grounded battery, resistance 779, upper left hand contact of sequence switch spring 780, winding of relay 778 to ground. This last mentioned circuit was previously in existence, but relay 778 was shunted by the presence of ground supplied by way of the lower armature and back contact of relay 7 78, and the inner left-hand armature and back contact of relay 777.

When sequence switch 700 reaches position 8, a circuit is also completed from ground, right-hand winding of relay 505, conductor 506, upper contacts of sequence switch spring 313, conductor 314, terminal 246, brush 247lower contact of sequence switch yspring 248, conductor 249, contact of sequence switch spring 848, register brush 845 and its fourth contact resistance 813 grounded battery. Relay 505 is energized in this circuit and locks up through its left-hand winding and left-hand armature and front contact to grounded conductor 504.

As soon as relay 777 is energized a circuit is completed from ground, winding of relay 315 (Fig. 3), upper contact of sequence switch spring 316, conductor 321, right-hand windin of marginal relay 507, conductors 508 an 322, terminal 250, brush 251, conductor 252, upper contact of sequence switch spring 857, high resistance 874, conductor 875, outer left hand armature and front contact of relay 777, low resistance 787, to grounded battery. Relay 315 is energized in this circuit but relay 507 being marginal, does not become energized due to the inclusion in it-s circuit of high resistance 874. The energization of relay 315 completes a circuit from grounded battery power magnet of sequence switch spring 300, armature and front contact of relay 315, lower left-hand and upper right-hand contacts'of sequence switch spring 317, armature and back contact of relay 318 to ground, for moving this sequence switch out of position 6 and into position 7.

As soon as sequence switch 300 leaves position 6, the energizing circuit for relay 777 is opened and this relay deenergizes, completing a circuit from grounded battery, power magnet of sequence switch 700, upper right-hand contact ofsequence switch spring 788, left-hand armature and back contact of relay 789, lower armature and front contact of relay 778, inner left-hand armature and back contact of relay 7 77, to ground for moving this sequence switch out of position 8 and into position 9. As soon as sequence 700 leaves postion 8, the circuit of, relay 778 is broken at sequence switch spring 780 and this relay deenergzes,

conductor 504. At the same time a circuit In positions 9 and 7 of sequence switches 700 and 300 respectively, the setting ofthe registers in Fig. 5 is continued. This operation is as follows:

When sequence switch 700 reaches position 8% a circuit is completed from ground, right-hand winding of relay 509, right-hand winding of marginal relay 510, conductor 511, contacts of sequence switch spring 323, conductor 307, terminal 235, brush 236, conductor 237, lower contact of sequence switch spring 238, conductor 239, contact of sequence switch spring 831, register brush 826 and its fourth contact, low resistance 782, tor grounded'ba-ttery. Since only a low re'- sistance is included inthis circuit, both relays 509 and 510 are energized in spite of the fact that relay 510`is marginal. These relays upon energiza-tion lock up to grounded is completed from grounded battery, right hand winding of relay 512, right-hand winding of marginal relay 513, conductor 514, lower contacts of sequence switch spring 325, conductor 322, terminal 250, brush 251, conductor 252, contact of sequence switch spring 833, register brush 828 and its first contact, high resistance 791, low resistance 792 to ground. Due to the presence of the high rcsistance 791 in this circuit, relay 513, which is marginal, does not become energized. Relay 512 does, however, become energized and locks up through its left-hand winding.

When sequence switch 700 reaches position 9, a circuit is completed from grounded battery, left-hand winding` of marginal relay 515, conductor 516, lower contacts of sequence switch spring 324, conductor 314, terminal 246, 'brush 2,47, contact of sequence switch spring 248, conductor 249, contact of sequence switch spring 841, register arm 836 and its fourth contact, left-hand contact of sequence switch spring 855, low resistance right-hand winding of relay 789 and thence' to ground. Relay 789 is energized in this circuit and due to the fact that only its low resistance winding was included in the `circuit, marginal relay 515 (Fig. is allowed to energize. Relay 515 upon. energization locks up to grounded conductor 504. Relay 789, upon encrgization locks up through its inner righthand armature and front contact and at the same time removes the shunting` ground which has been preventing the energization of relay 794. Relay 794 is now energized due to the completion of a circuit from grounded battery,resistance 779, righthand contact of sequence switch spring 780 and the winding of relay 794 to ground.

The energization of relay 789 completes a circuit from ground, winding of relay 318 (Fig. 3), upper contact of sequence switch spring 320, conductor 326, left-hand winding of marginalrelay 517, conductors 518, 310 and 311, terminal 240, brush 241, cori,-y 139 ductors 242 and 243, upper left-hand and lower' right-hand contacts of sequence switch spring 244, conductor 245, lower righthand contact of sequence switch spring 853 through the high resistance 874, conductor 875, outer right-hand armature and front contact of relay 789, low resistance 787 to grounded battery. Due to the presence of the high resistance 785, relay 517 cannot become energized. Relay 318 does, however, become energized and completes a circuit from grounded battery, power magnet of sequence switch 300, armature and back contact or" relay 315, upper lett-hand and lower right-hand contacts of sequence switch spring 317, armature and front contact o'f relay 318, to ground for moving this sequence switch out of position 7 and into position 8.

As soon as sequence switch 300 leaves position 7, relays 318 and 789 are deenergized. The deenergization of relay 789 completes a circuit from grounded battery, power magnet of sequence switch 700, upper left-hand contact of sequence switch spring 788, right-hand armature and back contact ot relay 777, lower armature and front contact of relay 794, inner right-hand armature and back contact of relay 789 to ground for moving this sequence switch out of position 9 and into position 10. As soon as sequence switch 700 leaves position 9, the holding circuit of relay 794 is broken and this relay deenergizes.

When sequence switch 700 reaches positionv 94j., a Circuit is completed from ground, right-hand winding of relay 519, right-hand winding of marginal relay 520, conductor 521, right-hand contact of sequence switch spring 327, left-hand contact of sequence switch spring 313, conductor 314, terminal l 246, brush 247, contact of sequence switch spring 248, conductor 249, contact of sequence switch spring 832,v register brush 827 and its sixth contact, high resistance 7 97 low resistance 782 to grounded battery. Due to the presence of high resistance 797 in this circuit, relay 520 does not become energized. Relay 519 does, however, become energized and locksV up to grounded conductor 504.

`When sequence switch 700 reachesI position 10, a circuit is completed from grounded battery, left-hand winding of marginal relay 522, conductor 523, upper contact of sequence switch spring 328, lefthand contact of sequence switch spring 306, conductor 307, terminal 235, brush 236, conductor 237, Contact of sequence switch spring 238, conductor 239, contact of sequence switch spring 842-, register brush 837 and its sixth contact, conductor 872, high and low resistance windings of relay 777, upper armature and back contact of relay 778 to ground; Due t0 the fact that the niet/,osa

high resistance right-hand winding of relay 777 has been included in this circuit, marginal relay 522 does not become energized. Relay 777 does, however, become energized and locks up through its inner left-hand armature and front contact and allows relay 778 to operate in the manner previously described. The energization ot relay 7 77 completes a circuit from ground, winding of relay 315 (Fig. 3), lower contacts or' sequence switch spring 319, conductor 329, right-hand winding of 1nargi nal relay 524, conductors 508 and 322, terminal 250, brush 251, conductor 252, lett hand contact of sequence switch spring 849, register brush 846 and its sixth contact, conductors 876 and 875, outer left-hand armature and front contact of relay 7 77, low re sista-nce 787 t0 grounded battery. Since only a low resistance is included. in this circuit, relay 524 is energized and locks up through its left-hand arma-ture. Relay 315 is also energized.

The energization of relay 315 completes a circuit from grounded battery, power mag net of sequence switch 300, armature and front contact of relay 315, lower left-hand and upper right-hand contactsl of sequence switch spring 317, armature and bach ccntact of relay 318 to ground for moving this sequence switch out ot position 8 and inte position 9. As soon as sequence switch 300 leaves position 8, relays 315 and 7 77 are deenergized. Relay 777 upon deenergization completes a circuit from grounded battery, power magnet of sequence switch '700, right-hand contact of sequence switch spring 788, lett-hand armature and back contact of relay 789, lower armature and front contact of relay 778, inner left-hand armature vand back Contact of relay 777 to ground, for moving this sequence switch out of position 10 and into position 11. As soon as sequence switch 700 leaves position 10, relay 77 8 is deenergized.

.When sequence switch 700 reaches posi tion 101.1-, a circuit is completed Jfrom ground, righhhand winding of relay 527, right-hand winding' of marginal relay 528, conductor 529, lower contact of sequence switch spring 328, upper contact of sequence switch spring` 308, conductor 307, terminal 235., brush 236, conductor 237, contact of sequence switch spring 238, conductor 239, contact of sequence switch spring 834, register brush 829 and its tenth contact, low resistance 782 to grounded battery. Since only a low-resistance is included in this circuit, relays 527 and 528 are both energized and lock up through their left-hand windings. it the same time, a circuit is completed from grounded battery, winding of relay 530, conductor 531, left-hand contacts of sequence switch spring 325, conductor 322, terminal 250, brush 251, conductor 252,

right-hand Contact ofY -sequence `Switch spring 849, register brush 851 and its sixth Contact to ground. Relay 530 is energized in this circuit and locks up through its leftliand armature and front contact to grounded conductor 504. f lVhen sequencesu'itch 700 rea-ches position 11, a circuit is completed from grounded battery, left-hand Winding'of marginal relay 525, conductor-526, left-hand contact ot sequence switch spring 327, left-hand contact of sequence lswitch 313, conductor 314, terminal 246, brush247, contact of sequence yswitch spring 248, conductor 249, contact of sequence switch spring 844, register brush 839 and its tenth contact, conductor 795, high and low resista-nce windings of relay 789 in series, upper armature and back Contact of relay 794 to ground. lRelay 789 is energizedin this'circuit, 'but due to the `fact that the high resistance lefthand winding of relay 789 was included in this circuit, marginal relay' 525'doe's not become energized.V RelayA 789'v upon energization locks up through4 its inner rightliand armature and front contact and in doing so removes the shunt from about the windingof relay 794, which relay therefore becomes energized. The energizati'on of relay 789 completes a circuit `from ground, winding of relay 318 (Fig. 3), upper contacts of sequence switch spring 319, conductor 330, right-hand winding of marginal relay 532, conductors 518, 310 and 311, terminal 240, brush 241, conductors 242 and 243, upper left-hand and lower right-hand contacts of sequence switch spring 244, conductor 245, left-hand contact of sequence switch spring 856, register brush 847 and its tenth contact, conductor 875, outer' righthand armature and front contact vof relay 789, low resistance 78,7 to grounded'battery. Since only the low resistance l7 87 is included in this circuit, relays 5,32 and 318 are both energized. j

The energization oi.:y relay 318 vcompletes a circuit from grounded battery, power inag- 'net of sequence switch 300, armature Vand back contactof relay 315, upper left-hand and lower right-hand contacts of sequence switch spring 317, armature and front contact of relay 318 to ground, to move sequence switch 300 out of position 9 and into position 10. Then sequence switch 300 leaves position 9, relays 318 and 789 are deenergized, but relay 532 remains energized due to the lfact that it has closed a locking circuit through its left-'hand winding and left-hand armature and 'front contact to grounded conductor 504.

The deenergization of relay 789 completes Va circuit from grounded battery, power magnet of sequence switch 700, upper left-hand contact of sequence switch spring 788, right-- hand armature and back contact of relay 777, lowery armature and front contact of relay 794, inner right-hand armature and back contact of relay 789 to ground, `for moving this sequence switch out of position 11 and into position 12. As soon as sequence switch 700 leaves position 11, relay 794 is deenergized.

When sequence switch 700 reaches position 12, a circuit is completed from grounded battery, power magnet 'of sequence switch 200, upper left-hand contact of sequence switchspring 206, conductor 253, contact of sequence switch spring 803 to ground, Vfor moving sequence switch 200 out of position -6 and into position 8. v

When sequence switch 200 reaches position 8, a circuit is completed from grounded battery, pow-er magnet of sequence switch 7 00, conductor 705, upper right-hand contact of sequence switch spring- 772, conductory 804, contact of sequence switchspring 254 to ground, for moving this sequence switch out' of position 12 and into position 16. v

In position 16 of sequence switch 700 the keys of the operators key set are released by means off magnets (not shown) which are actuated in position16 of the sequence switch. As soon as all of the keys have been released, circuits (not shown, but which are familiar to those skilled in the art) are completed for moving` vsequence switch 700 out of position 16 and'into position 1. The apparatus shown in Figs. 6 and 7 has now all been restored and is ready for reuse.

The positioning of the class controlling sequence switch 534 will now be described. This sequence switch has no normal position, but remains in whatever position it was last set until circuits are completed for moving it into a new position. The position in lwhich the class sequence switch stopped is It' will be recalled that in the present case,

relays 502 and 505 have been actuated. It will be assumed that when the sender was last used, the sequence switch 534 was resting in position 16. iis soon as sequence switch 300reaches position 7, at which time the class controlling relays above mentioned have been selectively positioned in accoidance `with the proper registration, sequence switch 534 will be moved out ofposition 16, through intermediate positions into position 14, which is the position in which this sequence switch controls the operation of the sender insuch a'inanner that a call may be directed toa localdesk. A circuit is completed fromv grounded battery, power magnet of sequence switch 534, upper letthand contact of sequence switch spring 535 right-hand armature and front contact of relay 502, conductor 536, lower contact ojf sequence switchspring 312 to ground. 'Sequence switch 534 moves into position 17 from which it is immediately moved due to the completion of a circuit from grounded battery, power magnet of sequence switch 534, upper right-hand contact of sequence switch spring 537, right-hand armature and back contact of relay 500 and thence to ground over conductor 536. The sequence switch moves into position 1 from which position it is moved by means of a circuit identical with that tracedl for moving it out of position 17. The sequence switch is moved out of position 2 by means of a circuit eX- tending from the upper left-hand contact of sequence switch spring 537, right-hand armature and front contact 'ofvrelay 505 to grounded conductor 536. The control of the sequence switch is alternated between the upper right-hand and upper left-hand contacts of sequence switch 537 until the sequence switch reaches position 10, at which time its power circuit is extended from the upper right-hand contact of sequence switch spring 535, right-hand armature and back contact of relay v507 to grounded conductor 536, for moving this sequence switch out of position 10 and into position 11. 1t is then moved out of position 11 by way of a circuit closed through the upper right-hand contact of sequence switch spring 537. From position 12 the sequence switch is moved into position 13 by means of a circuit closed through the upper left-hand contact ofsequence switch spring 535 and the righthand armature and front contact of relay 502. The upper right-hand contact of sequence switch spring 537 then serves to advance the sequence switch out of position 13 and into position 14. An inspection of the circuits will show that in position 14 there is no circuit in existence for advancing the sequence switch 534. It therefore, remains in this position. Relay 538 is energized in parallel with the power magnet of sequence switch 534 during the setting movement of the class register switch. The purpose of this is to prevent the closing of the fundamental circuit before the class register has been fully positioned. As soon as the class register has been fully positioned, relay 533 deenergizes and closes a circuit from grounded battery, power magnet of sequence switch 400 (Fig. 4), lower right-hand contact of sequence switch spring 401, conductor 402, contacts of sequence switch spring 334. conductor 335, armature and back contact of relay 538 to ground for moving this sequence switch out of position 1 and into position 4.

With sequence switch 400 in position 4, sequence switch 300 in position 10 and sequence switch 200 in position 8, the fundamental circuit for controlling the district brush selecting operation is completed, it being remembered that sequence switch is at this time in position 5.

The fundamental circuit extends from grounded battery, left-hand winding of relay 106, lower right-hand contact of sequence switch spring 121, lower left-hand contact of sequence switch spring 125, conductor 231, terminal 230, brush 229, inner right-hand armature and front contact of relay 223, upper left-hand and lower righthand contacts of sequence switch spring 222, conductor 242, brush 241,` terminal 240,

conductors 311 and 331, contact of sequence 2 switch spring 332, conductor 333, contacts of sequence switch spring 403, winding of stepping magnet 404, armature and baclr contact of the 0 counting relay, conductor 405, contacts of sequence switch spring 336, conductor 337, upper contact of sequence switch spring 406 to ground. Relay 106 and stepping relay 404 are energized in this circuit. The energization of relay 106 completes a circuit from grounded battery, power magnet of sequence switch 100, conductor 117, left-hand cont-acts of sequence switch spring 124, inner right-hand armature and front contact of relay 106, upper contacts of sequence switch spring 109 to ground, for moving this sequence switch out of position 5 and into position 6.

In position 6 of sequence switch 100, relay 106 is maintained energized by means of a circuit closed through its left-hand winding and left-hand armature and front contact and the upper right-hand contact of sequence switch spring 121 to ground over the path described.

With sequence switch 100 in position 6, and with relay 106 energized, a circuit is completed from grounded battery, winding of up-drive magnet 126, upper right-hand and lower left-hand contacts of sequence switch spring 124, right-hand armature and front Contact of relay 106, upper contacts of sequence switchspring 109 to ground.

Referring now to Fig. 4, it will be noted that the energization of stepping relay 404 completed a circuit from ground,upper lefthand contact of sequence switch spring 407, armature and front contact of relay 404, contact of sequence switch spring 403, conductor 409, left-hand contact of sequence switch spring 338, conductor 339, lower lefthand contact of sequence switch spring 410, lower left-hand contact of sequence switch spring 411, conductor 412, right-hand armature and front contact of relay 509, lefthand armature and front contact of relay 515, right-hand armature and front Contact of relay 510, thence to the armature and back contact of the No. 3 counting relay (Fig. 4), winding of the No. 3 counting relay, contact of sequence switch spring 413 to grounded battery. The No. 3 counting relay is energized in this circuit and prepares a locking circuit for itself including the winding yof the No. 3 counting relay. The No. 3 counting relay does not, however,

famose become energized since its winding is shunted by the presence of direct ground controlled at the armature of stepping relay 404.

In response to the energization of up-drive magnet 126, the district brush shaft is moved upwardly. As soon as commutator brush 127 engages a conducting segment of commutator 128, stepping relay 404 is shunted down due to the completion of a circuit eX- tending from grounded battery, left-hand winding of relay 106, left-hand armature and front contact of relay 106, upper righthand contact of sequence switch spring 1 21, lower right-hand contact of vsequence switch spring 125, commutator 128, commutator brush 127 to ground. Relay 106 is maintained energized in this circuit but relay 404 is deenergized and causes the cnergization of the No. 3 counting relay in the well-known manner. As soon as commutator brush127 engages an insulating segment of commutator 128, the shunt path to ground is opened and relay 404 is again energized to cause the energization of the No. 2 counting relay. The advance of the district brush shaft con.- tinues and the countingrelays are successively actuated. After the brush shaft has been advanced three steps, a circuit is completed from grounded battery, winding of the No. 0 counting relay, armature and back contact of relay 414, conductor 415 and thence through the right-hand armatures and front contacts of the No. 1, 2 and 3 counting relays in series to ground at sequence switch` spring 407.l YVhen the district switch has completed its fourth brush selecting step, relay 404 Vis again deenergized and allows the No. 0 counting relay and relay 416 in paralleltherewith to become energized. The energization of the 0 counting relay opens the lower branch of the fundamental circuit and since commutator brush127 is now engaging an insulating segment of commutator 128, the locking circuit of relay 106 is broken and this relay deenergizes and completes a circuit from grounded battery, winding of power magnet of sequence switch 100, conductor 117, lower contacts of sequence switch spring 114, inner right-hand armature and back contact of relay 106, upper contacts of sequence switch spring 109 to ground, for moving this sequence switch out of position 6 and into position 7. The deenergization of relay 106 also opens the circuit of up-drive magnet 126 and causes the district brush shaft to be brought to rest in a positionlsuch that upon subsequent upward movement of the brush shaft the fourth set of brushes will be tripped.

1n position 7 of sequence switch 100, a circuit is completed from grounded battery, winding of trip magnet 122, right-hand contact of sequence switch spring 109 to ground. The trip rod isy actuated in the wellknown manner. i

Referring to the sender circuit in Fig. 4, theenergization of relay 416 completes a circuit extending from grounded battery, power magnet of sequence switch 400, up? per right-hand contact of sequence switch spring 401, armature and front contact of relay 416 to ground for movingy this sequence switch out of position 4 and into position 6. i

With sequence switch 100 in position7 and sequence switch 400 in position 6k the fundamental circuit is again completed to control group selection at the district switch shown in Fig. 1. This circuit is identical with that described forl controlling brush selection. Relay 106 upon energization locks up as before and causes the advance of sequence switch 100 out of 4position 7and into position 8 by means of circuits identical with those traced for moving this sequence switch from position 5 to position 6. Relay 404 is again'enengizedy upon thesecond completion of the fundamental circuit'. It is to be noted that when sequence switch 400 left position 4 the locking circuits of the counting relays were opened at sequence switch spring 413. lIn position 6 of sequence switch 400, relay 414 isenergized due to the existence of a. circuit extending from grounded battery, winding of relay 414, upper contacts of sequence switch spring-417, conductor 418, riglithand armature and front contact of relay 524,v conductor 5.39, contact of sequence switchmspringv 340 to ground.. i y.

The energization of relay 404 at thisrtime lcompletes a circuit from ground, upper leftf hand contact'of sequence switch spring 407, armature and front contact of relay5404, contact'y of sequenceswitch spring 408, conductor 409, left-hand contact of sequence switch spring 338, conductor 339, lower lefthand contact of sequence switch spring 410, lower right-hand contact of sequence switch spring 411, conductor 419, right-hand armature and front contact of relay 519, lefthand armature and back contact of relay 522, inner right-hand armature and back contact of relay 520, thence to conductor 415 F ig. 4) right-hand armature and front contact of relay 414, armature and back contact of the No. 9 counting relay, the winding of the No. 9 counting relay, contactv of sequence switch 413 to grounded battery, The N o. 9 counting relay is energized in this circuit and completes av locking circuit for itself including the No. 9 counting relay. The No. 9 counting-'relay is not energized, however, dueto the shunt circuit extending to ground by way of the armature and front contact of relay 40.4.

In position 8of sequence switch 100 land with relay 106 energized the circuit of updrive magnet 126 is again completed and the district brush shaft is moved upward in 

